1. Field of the Invention
The present invention generally relates to a method of reducing Ethernet power consumption by reducing the Ethernet link speed to a minimum rate required for current link traffic. More specifically, the method includes providing a method for automatically commanding an Ethernet adapter/cable to decrease or increase a link rate by dynamically auto-negotiating the Ethernet to a lower or higher link rate without user intervention.
2. Description of the Related Art
There is increasing industry focus on energy efficiency and decreasing power consumption in datacenter or Dynamic Host Configuration Protocol (DHCP) servers. As an example, a company may lose a significant bid because their server consumes a few more watts of power than a system of a competitor. Ethernet is a pervasive technology in datacenter servers and therefore contributes to the total power consumed within the datacenter. A single datacenter server will probably contain at least one (and often multiple) Ethernet adapter(s)/cable(s). The faster the adapter/cable, the more power is consumed. Transmission protocols of 10 Mbps-100 Mbps often waste power. If the power consumed by the Ethernet adapters/cables can be decreased, the total power consumption of the server will decrease accordingly. Even a few watts of power reduction per server can be a significant savings when multiplied by the number of servers within a datacenter, which can number in the hundreds or even thousands.
Schemes have been devised such as “Energy Efficient Ethernet” which uses Adaptive Link Rate (ALR) technology to dynamically increase or reduce the link rate based on the link bandwidth requirements. Accordingly, the Ethernet link speed is adapted to match the needs of a device. When the Ethernet link rate is decreased, power consumption in the Ethernet adapter/cable and switch decreases accordingly. In checking e-mail, for instance, 100 Mb/s would be enough, but the network controller would shift to 1 Gb/s when downloading a large file. As an example, a link rate decrease from 1 gigabit/second (Gbps) to 100 megabit/second (Mbps) results in a power savings of approximately 4 watts. Ten-gigabit links—expected to be widespread by year 2010—use 10 to 20 W more power than 100 Mb/s links, while 1 Gb/s uses about 4 W more. Researchers estimate that with networking devices in homes, offices, and data centers running at 1 Gb/s, switching to 100 Mb/s whenever possible could save more than US$300 million in energy costs. The savings would be even greater if the links were switching between 10 Gb/s and 100 Mb/s. However, in addition to being time consuming (up to 2 seconds), this scheme will require a new Ethernet adapter/cable and switch hardware, or a complete redesign of the network-interface controller system, and therefore will not be compatible with the existing equipment of a customer.
Another scheme called a “low-power idle,” proposes transferring data on an Ethernet link at the highest possible rate and then putting the network controller chip into a sleeplike state. However, turning on a dormant network card quickly is a challenge.